Format attribute required on referenced date

Error FX-SCH-A-000465 Factur-X

Attribute '@format' is required in this context.

Mandatory rule: As long as it is violated, the invoice is invalid and will be rejected by validators.
What is wrong

The @format attribute is missing from qdt:DateTimeString for the issue date.

What the rule means

The @format attribute identifies the format of the date value. Without it, the date format is not specified in this context.

Please add the format attribute to the referenced date

The format designation is missing from the issue date of the referenced document. Add it so the invoice can be validated again.

What to do
  1. Locate qdt:DateTimeString for the issue date of the referenced document.
  2. Add the @format attribute there.
  3. Generate the invoice again and validate it again.
Technical details

The test directly checks whether the @format attribute is present in the context of qdt:DateTimeString.

Where the rule applies

The rule applies to qdt:DateTimeString in the issue date of the referenced document.

Context (rule/@context)
/rsm:CrossIndustryInvoice/rsm:SupplyChainTradeTransaction/ram:ApplicableHeaderTradeSettlement/ ram:InvoiceReferencedDocument/ram:FormattedIssueDateTime/qdt:DateTimeString
Test expression (assert/@test)
@format